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Posted to issues@trafficcontrol.apache.org by GitBox <gi...@apache.org> on 2020/01/21 18:06:41 UTC
[GitHub] [trafficcontrol] rob05c opened a new issue #4311: Fix ORT to
atomically place files.
rob05c opened a new issue #4311: Fix ORT to atomically place files.
URL: https://github.com/apache/trafficcontrol/issues/4311
## I'm submitting a ...
<!-- (check all that apply with "[x]") -->
<!--- security vulnerability (STOP!! - see above)-->
- [x] bug report
- [ ] new feature / enhancement request
- [ ] improvement request (usability, performance, tech debt, etc.)
- [ ] other <!--(Please do not submit support requests here - see above)-->
## Traffic Control components affected ...
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- [ ] CDN in a Box
- [ ] Documentation
- [ ] Grove
- [ ] Traffic Control Client
- [ ] Traffic Monitor
- [ ] Traffic Ops
- [x] Traffic Ops ORT
- [ ] Traffic Portal
- [ ] Traffic Router
- [ ] Traffic Stats
- [ ] Traffic Vault
- [ ] unknown
## Current behavior:
ORT does not atomically place new files. It uses `cp`, which is not atomic.
This means if somethings fails – Perl crashes, the OS crashes, the syscall fails for some reason – the file will be half-written, causing ATS reloading to fail.
## Expected / new behavior:
The proper procedure is to make a new temporary file, and then call `mv`, which is guaranteed to be atomic, and either succeed or fail.
Code is here:
https://github.com/apache/trafficcontrol/blob/master/traffic_ops/ort/traffic_ops_ort.pl#L1575
## Minimal reproduction of the problem with instructions:
Difficult to reproduce. You'd have to run ORT and kill the Perl when it was in the middle of a file write. But it would definitely happen. And then your ATS reload or restart would fail.
## Anything else:
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[GitHub] [trafficcontrol] rob05c commented on issue #4311: Fix ORT to
atomically place files.
Posted by GitBox <gi...@apache.org>.
rob05c commented on issue #4311: Fix ORT to atomically place files.
URL: https://github.com/apache/trafficcontrol/issues/4311#issuecomment-577309029
Also: it's common practice to run the OS temp directory on a different filesystem for security reasons, which will cause `mv` to be non-atomic as it then has to actually copy bytes.
Therefore, the temporary file should be in the same directory as the real file, to ensure it's on the same filesystem.
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